Motor graders are used to prepare the grade of a ground surface in an area. Grading can be provided for numerous reasons, including for roads, providing foundation, and the like where a uniform surface is desired for an end application. Motor graders generally are elongated vehicles that include multiple implements for performing such tasks.
Implements can include grader blade systems such as drawbar, circle mount, and moldboard (DCM) systems, dozer blade systems, scarifier systems, and the like. These implements are mounted to the motor grader frame for utilization as required. Mounting locations include, but are not limited to, a front mounting position, mid-mounting position, and back mounting position. The front mounting position of an implement is in the front of the frame, and specifically, where the implement extends in front of front wheels of the motor grader. This mounting position is typically for dozer blade systems. Similarly, the back-mounting position is at the back end of the frame and can include the ripper system and scarifier system.
Implements are also mounted onto the frame in a mid-frame mounting position. Mid-frame mounting, or mid-mount implements are positioned between the front end and back end of the motor grader. Typical implements having a mid-mount include the DCM system and scarifier system.
One of the main challenges for mid-mounted implements, such as scarifier systems, is spacing with other systems of the motor grader. Other systems include the wheels and axle, hydraulic systems, other implement systems, and the like. For example, many motor graders mid-mount both the DCM system and scarifier system between the cab of the motor grader and front wheels. The DCM system includes a frame with a drawbar that extends from a position behind the scarifier system and toward the front end of the frame for attachment to the frame between the front wheels. Thus, when mounting a mid-mount scarifier, not only do mounting, structural support, movement, and operational requirements, need to be taken into consideration, but additionally, the positioning and shape of the frame and other assemblies and systems of the motor grader.
A typical mid-mounted scarifier system includes drawbar arms that are secured to the motor grader frame and receive a scarifier carriage having teeth used to scarify the ground. To support and move the carriage from a non-working position to a working position often a complex linkage assembly is also coupled to the frame. Such linkage assemblies can include lift arms or rods, ball joints, shafts, mounting plates, adjustable lift cylinders, welded ball studs, and the like that are utilized to reinforce and move the drawbar arms.
While current scarifier systems allow movement as required by a user, systems remain complex, and spacing with regard to other assemblies and systems of the motor grader remain a concern. The linkage assembly often disrupts the line of sight of a user, making seeing objects in front of the machine and thus motor grader operation more difficult. Spacing between the scarifier system and other systems can be insufficient to prevent collision between the systems during operation. As an example, when traversing uneven and bumpy terrain, the drawbar arms or accompanying linkage assembly of the scarifier system can engage the tires, causing undesired wear and damage to the tires and scarifier system. Similarly, scarifier systems can engage other implements such as the DCM system causing damage and wear to each, including in some cases bending of the linkage assembly. Moreover, because of the complexity of the linkage assembly, and placement on the frame, typically replacing and retrofitting current scarifier systems is impracticable.
Some systems minimize or eliminate linkage assemblies in the scarifier system. As an example system where linkage is eliminated, the Dresser™ scarifier assembly provides a pivot pin secured to the frame adjacent a front end with side-by-side arcuate drawbar arms extending around each tire and extending to the scarifier carriage. Instead of a linkage assembly, dual hydraulic cylinders are welded above the front wheels at a first ball stud, and the hydraulic cylinders extend and are welded to the arcuate drawbar arms at a second ball stud adjacent the carriage and front wheels.
Still, even when linkage assemblies are minimized or eliminated, doing so results in additional design constraints. These can include additional costs, additional manufacturing time, difficulties in replacement, system wear, interference with line of sight of the driver, lack of ease and design flexibility for retrofitting, and the like.